Implement exception logging #220.

Created custom error handler;
Applied default error handling functionality

Author: Maksym Novik

app/etc/di.xml

@@ -209,6 +209,7 @@
     <preference for="Magento\Framework\MessageQueue\Bulk\ExchangeFactoryInterface" type="Magento\Framework\MessageQueue\Bulk\ExchangeFactory" />
     <preference for="Magento\Framework\MessageQueue\QueueFactoryInterface" type="Magento\Framework\MessageQueue\QueueFactory" />
     <preference for="Magento\Framework\Search\Request\IndexScopeResolverInterface" type="Magento\Framework\Indexer\ScopeResolver\IndexScopeResolver"/>
+    <preference for="\Magento\Framework\GraphQl\Query\ErrorHandlerInterface" type="\Magento\Framework\GraphQl\Query\ErrorHandler"/>
     <type name="Magento\Framework\Model\ResourceModel\Db\TransactionManager" shared="false" />
     <type name="Magento\Framework\Acl\Data\Cache">
         <arguments>

lib/internal/Magento/Framework/GraphQl/Query/ErrorHandler.php

@@ -0,0 +1,29 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+declare(strict_types=1);
+
+namespace Magento\Framework\GraphQl\Query;
+
+/**
+ * Class ErrorHandler
+ *
+ * @package Magento\Framework\GraphQl\Query
+ */
+class ErrorHandler implements ErrorHandlerInterface
+{
+    /**
+     * Handle errors
+     *
+     * @param \GraphQL\Error\Error[] $errors
+     * @param callable               $formatter
+     *
+     * @return array
+     */
+    public function handle(array $errors, callable $formatter):array
+    {
+        return array_map($formatter, $errors);
+    }
+}

lib/internal/Magento/Framework/GraphQl/Query/ErrorHandlerInterface.php

@@ -0,0 +1,26 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+declare(strict_types=1);
+
+namespace Magento\Framework\GraphQl\Query;
+
+/**
+ * Interface ErrorHandlerInterface
+ *
+ * @package Magento\Framework\GraphQl\Query
+ */
+interface ErrorHandlerInterface
+{
+    /**
+     * Handle errors
+     *
+     * @param \GraphQL\Error\Error[] $errors
+     * @param callable               $formatter
+     *
+     * @return array
+     */
+    public function handle(array $errors, callable $formatter):array;
+}

lib/internal/Magento/Framework/GraphQl/Query/QueryProcessor.php

@@ -8,8 +8,8 @@
 namespace Magento\Framework\GraphQl\Query;
 
 use Magento\Framework\GraphQl\Exception\ExceptionFormatter;
-use Magento\Framework\GraphQl\Schema;
 use Magento\Framework\GraphQl\Query\Resolver\ContextInterface;
+use Magento\Framework\GraphQl\Schema;
 
 /**
  * Wrapper for GraphQl execution of a schema
@@ -27,15 +27,25 @@ class QueryProcessor
     private $queryComplexityLimiter;
 
     /**
-     * @param ExceptionFormatter $exceptionFormatter
-     * @param QueryComplexityLimiter $queryComplexityLimiter
+     * @var \Magento\Framework\GraphQl\Query\ErrorHandlerInterface
+     */
+    private $errorHandler;
+
+    /**
+     * @param ExceptionFormatter                                     $exceptionFormatter
+     * @param QueryComplexityLimiter                                 $queryComplexityLimiter
+     *
+     * @param \Magento\Framework\GraphQl\Query\ErrorHandlerInterface $errorHandler
+     * @SuppressWarnings(PHPMD.LongVariable)
      */
     public function __construct(
         ExceptionFormatter $exceptionFormatter,
-        QueryComplexityLimiter $queryComplexityLimiter
+        QueryComplexityLimiter $queryComplexityLimiter,
+        ErrorHandlerInterface $errorHandler
     ) {
         $this->exceptionFormatter = $exceptionFormatter;
         $this->queryComplexityLimiter = $queryComplexityLimiter;
+        $this->errorHandler = $errorHandler;
     }
 
     /**
@@ -67,6 +77,8 @@ public function process(
             $contextValue,
             $variableValues,
             $operationName
+        )->setErrorsHandler(
+            [$this->errorHandler, 'handle']
         )->toArray(
             $this->exceptionFormatter->shouldShowDetail() ?
                 \GraphQL\Error\Debug::INCLUDE_DEBUG_MESSAGE | \GraphQL\Error\Debug::INCLUDE_TRACE : false